Pay closer attention, and other distinctions become apparent, including how each side makes the sign of the cross, when they celebrate Easter and how they refer to the Holy Spirit.

In the nearly 1,000 years since Christianity split into East and West, the two sides have grown farther and farther apart. Yet basic compromises -- or simply agreeing to disagree -- could resolve most issues, according to representatives from both sides who recently met at Georgetown University.

The trouble, it turns out, is the pope.

After a recent meeting of the North American Orthodox-Catholic Theological Consultation, two dozen participants from both sides issued a statement aimed at guiding the churches back to their shared roots. Members could imagine a reunited church with a new calendar and old prayers, but “the central problem is the role of the pope,” said Paulist Fr. Ronald G. Roberson, associate director of the U.S. Conference of Catholic Bishops’ ecumenical office.

“We can agree on everything, but that would be the sticking point,” agreed the Fr. Mark Arey, spokesman for the Greek Orthodox Archdiocese of America, of the hypothetical bishop of Rome and his decentralized authority over clergy and laity worldwide.

Arey described the North American vision as a “nice hypothesis,” whose application would require the Vatican and dozens of Orthodox leaders to sign off on changes that are guaranteed to upset millions of adherents.

The global version of this ecumenical effort—the Joint International Commission for Theological Dialogue between the Catholic Church and the Orthodox Church—also recently chewed over the idea of becoming sister churches with the pope as a titular head.

But Metropolitan Hilarion, speaking on behalf of the Russian Orthodox Church, quickly and decisively denied that a “breakthrough” had been achieved at the group’s September summit in Austria.

When dealing with institutions that have been divided for half of their 2,000-year history, Arey said, change comes gradually, over generations.

While bringing the churches into full communion could take several lifetimes, establishing a shared Easter date could—and should—happen in a matter of years, theologians argue.

Both Eastern and Western Easter overlapped this year, and will fall on April 24 in 2011, converging again in 2014 and 2017. They conflict again until 2034.

In 1997, the World Council of Churches met in Aleppo, Syria, and proposed scientifically updating both calendars. Orthodox Christians have resisted changing their traditional approach, however, even though their method will eventually push Easter into the summer.

Common holidays aren’t required for a unified church, Arey said, noting that several Orthodox groups, including the large Russian church, still celebrate Christmas in January. But others still consider the Easter disagreement, in Roberson’s words, “a big deal.”

“It really weakens our witness when Christians can’t even agree on the same day to proclaim the resurrection of our Lord,” Roberson said. “We’re saying publicly that we really need to resolve this.”

Otherwise, after decades of dialogue between Orthodox and Catholic leaders in North America and abroad, Roberson said the larger vision statement will help Christians “start to see, maybe dimly, the outlines of what this might look like.”

“We can fantasize, or blue sky a little bit, about what kind of unity that we can achieve someday,” he said.

Arey, from the Greek Orthodox, agreed.

“We’ve been talking and agreeing about things for years, and all of that creates a climate and an atmosphere which is very constructive,” Arey said. “At the international level, they will see our statement and it will stir them on.”